Air foil section



,sept.27, 1960 Rw. LD Em., 2,954,208

' AIR SECTION Filed Jan. 9, 1953 Mlm IN VEN TOR A j* 4% 4 M x ATM/MVSnited States Patent AIR FOIL SECTION Filed Jan.9, 1953, Ser. No. 330,464

3 Claims. (Cl. 253-77) This invention'relates toair foils and moreparticularly to a hollow air foil section Vandmeth'od of making thesame. f

An object of this invention4 is to form a hollow air foil section suchas a compressor blade from sheet material having a mountingmeansintegrally formed therewith.

Another object of this invention is' to form a hollow internallyreinforced compressorblade from sheet material wherein the mounting orfoot portion integrally formed with the blade is adapted torfixedlyattachthe blade to a support. l W

A more specific object of this invention is to provide a method forforming a hollow light weight compressor blade of relatively large sizefrom sheet material by folding the sheet, brazing edges of the sheettogether, and internally reinforcing the blade portion thus formed. Amounting means for the blade portion is integrally formed therewith andhas at least a portion thereof wrapped about a solid ller which forms apart of the foot whereby the blade portion is rigidly supported.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

ln the drawings:

Fig. 1 shows a side View of air foil section embodying the presentinvention.

Fig. 2 is an end View of Fig. 1.

Fig. 3 is a section along line 3-3 in Fig. 1.

Fig. 4 is a section 4along line 4-4 in Fig. 1.

Fig. 5 is a section along line 5 5 in Fig. 1.

Fig. 6 is an enlargement of encircled portion 6 in Fig. 3.

Fig. 7 is an enlargement of the encircled portion 7 of Fig. 3.

Fig. 8 is one modification of Fig. 4.

Fig. 9 is another modification of Fig.`4.

Blades or airfoil sections for turbines, compressors and the like areused in many sizes and lengths according to the speciiic stage withinthe machine. In certain stages the blades are relatively small and aremade by various methods from conventional materials in solid form. Asthe size of the blade increases the weight of the material thereon has adefinite bearing on the use and etliciency of the unit.

For this reason it is often desirable to reduce the weight of bladesover ve to six inches in length for example. In order to accomplish thisend, sheet metal fabricated blades have many useful features. Howeverthese blades have lacked strength, particularly at the joining portionsbetween the airfoil section and the foot, which condition has preventedtheir widespread use.

This invention attacks the problem in a different manner than prior artadvances and removes the retarding portions toward the use of sheetmetal blade. This is accomplished by providing a strong and unitary foot2 Y structure integral with the airfoil section which can be readilymade in large scale production.

ln the drawings reference numeral 20 designates an air foil memberparticularly adapted for use in axial llow compressors wherein bladesrelatively light in weight and large in size are often required. Thisair foil member 20, has a blade or air foil section 22 and a foot orroot portion 24 integrally formed therewith. This member is formed fromka single sheet of material which is cut into a predetermined shape.lAfterthe sheet is cut,V it is folded so that two opposed edges are inabutting relation whereby they may be joined by `brazing (Fig. 6) `orany other suitable method to form a blade 22 having integrally attachedthereto the foot 24.

The foot 24 includes foot mounting portion 36` (Fig. 4) that hasextending arms 38 and 40 integral with the blade wrapped around a solidller or support 42 and may be more rrnly attachedV to support` 42 by`some suitable method such as brazing. YThe blade is further providedwith clamping strips which form clip-like members 43 (Fig. l) that `arewrapped about and brazed to the ends of ller 42. The strips 43 are usedto prevent any slip between the blade and the liller and are also usedto make the outer dimension of the foot 24 conform throughout its fullextent. As shown in Fig. l, clip-like i members 43 extend beyond theleadingand trailing edges of the airfoil member 20.

The foot 24 of the finished blade may be then inserted in a cooperatingslot in a mounting ring or member of the compressor thereby securelyattaching the blade 22 to the mounting through the foot 24. Thecooperating slot in the mounting 37 is dimensioned to snugly accommodatethe foot 24, and has angular portionsv 41 arranged for forming anarrowed necked portion 39 therebetween in the mounting 37. This neckedportion 39 formed of angular portions 41 provides an interlockingretaining means and serves to maintain the blade in position againstcircumferential movement relative to the slot.' Thus it will be apparentthat when the blade is mounted, the airfoil section and its footmounting will be rrnly clamped to provide a secure attachment for theair foil section. This type of construction, wherein the attaching meansis integrally formed with the air foil section, provides a continuoussurface in a one-piece structure without joints and thereby eliminatesweakened portions normally present at the junction of the blade and rootwherein joining techniques such as brazing or welding have been used.

An internal reinforcing member 25 which is included within the air foilsection 22 (Fig. 3) comprises a V- shaped element (Figs. 3 and 7) havingan apex 29 joined to one internal surface 32 and the connected extendingarm portions 28 and 30 joined to the other internal surface 34 of theair foil section.

The blade as herein disclosed may be used with or without integralreinforcing means depending upon the thickness of the sheet `and theoverall dimensions. If reinforcing means are employed, the bladestructure should be of suicient strength to support the strut or bracewhich may be suitably attached to the internal surface of the blade asshown in Fig. 3.

A modification, as seen in Fig. 9, shows a structure providingadditional reinforcing means for the air foil section. This is achievedby having a portion Si) of the liller 42 extend into the `air foilsection 22 to provide additional reinforcing means adjacent the root,where blade failures generally occur.

Another means of reinforcing the blade is through the use of plasticfillers. Any suitable material such as: rubber-like materials,thermosetting or thermoplastic resins etc. in fact any material whichwill withstand the ambient temperature condition may be used. A plastica 2,954,298v lee Patented sept. 27, raso.

reinforcing means 46 as shown in Fig. 8, may be used and will provideadditional rigidity and impart strength to the blade. It is understoodthat similar llers may be used in connection with any Vof the bladestructure shown.

It is `apparent that Ythis invention is partieularly directed to animproved blade and to a method of attaching the blade in an element ofan axial llow compressor. The attachment in the present instance isaccomplished by having the lroot portions of the air foil memberintegrally formed with the air foil section. The extending root portionswhich are wrapped about a solid ller may be brazed thereto to form acomposite reinforced foot. When said foot is inserted into a suitablyshaped recess in a supporting ring or rim, a unitary connection -will-result between the lblade portion of the air foil member and thesupport.

While the embodiment of the present invention, as herein disclosed,constitutes a preferred f orm, it is to be understood that other formsmight Ybe adopted.

What is claimed is as follows:

1. An airfoil member comprising: a hollow air'foil portion having apredetermined cross-sectional shape, and a foot portion integrallyformed with said airfoil pon tion for supporting said `airfoil portionlin a mounting support, a solid ller member for'said foot portion havinga non-curvilinear cross-sectional shape, said foot portion including apair of arm portions Wrapped around the sides of and embracing a centralsection of said filler member, and a pair of clip members wrapped around4 `and brazed to the ends of said filler member and extending Abeyondthe 4leading andtrailing edges of said airfoil portion, said clipmembers preventing slippage between said foot portion and said fillermember and providing a uniform outer surface on said ller member.

2. A hollow airfoil member as set forth in claim l wherein the airfoilportion has `reinforcing means therein.

3. The hollow airfoil member as set forth in claim 1 wherein a portionvonly of the filler member extends into a portion of `the airfoil'section for providing `support for the airfoil section.

References Cited in the file kof this patent UNITED STATES PATENTS994,166 Kienast .Tune 6, 1911 2,431,660 Gaudenzi Nov. 25, 1947 2,512,264Brauchler June 20, 1950 2,520,373 Price Aug. 29, y1950 2,537,739 ChiltonJan. 9, 1951 2,559,131 Oestrich July 3, 1951 2,577,336 Lampton Dec. 4,1,951 2,642,263 Thorp June 16, 1953 2,656,146 ,Sollinger Oct. 20, 19532,823,894 Gerdan Feb. 18, 1958 FOREIGN PATENTS 42,539 Austria `lune 10,1910 131,574 Australia Mar. 1, 1949 628,036 .Great Britain Aug. 22,19.49 1,007,303 France Feb. 6, 1952

